Steam-engine of the double-cylinder type



J. G. McKEAN.

STEAM ENGINE OF THE DOUBLE CYLTNDER TYPE.

APPLICATION FILED JUNEZ, I917- Patented Mar. 30, 1920.

1702.11, G HGKGCUU.

JOHN G. McKEAN, or WHITLEY BAY, ENGLAND.

STEAM-ENGINE OF THE DOUBLE-CYLINDER TYPE.

Specification of Letters Patent.

Patented Mar. 30, 1920.

Application filed June 2, 1917. serial No. 172,533.

To all whom z'tmay concern:

Be it known that I, JOHN-GRAVES Mo- KEAN, a subject of the King of GreatBritain and Ireland and the Isle of Man, and a resident of WhitleyBay,Northumberland, England, have invented new and useful Improvements inSteam-Engines of the Double-Cylinder Type, of which the following is aspecification.

This invention has reference to improvements in steam engines of thedouble cylinder type and consists in the provision of means comprising acontracted or ejector throat which is formed at the junction of twobranch pipes, one connected to the exhaust port of each cylinder, with acommon exhaust pipe so that the energy contained in the steam at theterminal pressure in one cylinder is utilized to create for the latterpart of the stroke a less absolute back pressure on the piston of theother cylinder than that existing in the region to which the cylindersfinally exhaust, provided that this region does not contain a perfectvacuum.

According to this invention branch exhaust pipes from the cylinders of adouble cylinder engine, preferably having cranks at right angles orapproximately so, or an engine in which the movements of the pistonswould give the same results, such as pumping engines of the WVorthingtontype, are connected to a common exhaust pipe; a

contracted or ejector throat being formed at the junction of said pipes,the cross sectional areas of the throat being less than the crosssectional area of the said branch pipes. The steam contained in thecylinder, the piston of which has completed its stroke and which is at ahigher pressure than that existing in the common exhaust pipe which isopen to the space in front of the piston of the other cylinder passesthrough this throat so that for the latter part of the stroke the backpressure in front of the piston of said other cylinder is reduced.

In order that others skilled in the art to which my invention relatesmay properly understand the same I havehereunto ap- V two cylinders of asteam engine in which the one piston is at the end of its stroke-whilethe other piston is at the middle of its stroke.

Fig. 2 illustrates, also in diagram form,

the exhaust from each cylinder connected to Y decidedly advantageous.

a common exhaust pipe fitted or constructed according to theimprovements of this in vention.

Referringv to these drawings In carrying this invention into effect orpractice the ejector consists of a branch pipe, (1. and 22 connectedfrom the exhaust port of each cylinder a and b to a common exhaust pipe0, having at the junction of said two branch pipes, a and 6 a contractedor ejector throat, d, the cross sectional areas of said branch pipesalso being contracted toward the said junction.

In slow running engines, valves e, preferably of the ball type, and withlugs or the like, f, to limit the lift, may be placed between theexhaust ports and the throat of the ejector, d, in order to prevent thereturn of the higher pressure in the exhaust pipe, due to the weakeningaction of the ejector when the exhaust operating it falls in pressure.

The ejector action when the steam is excylinder first uncovers the port.At this point, the steam pressure will be that due to the terminalpressure in the cylinder, and this pressure energy will be convertedinto kinetic energy at the throat of the ejector 03, thereby causing ahigh velocity at that point with consequently increased ejecting power.As the exhaust remains open, the pressure will drop, as will also thevelocity past the throat of the ejector, and consequently the ejectingpower will be decreased. Were it not for the ejector action, the backpressure in the other cylinder would be equivalent to the pressureexisting in the common exhaust pipe. It therefore follows that when theejector action weakens, the steam in the powerful when the exhaust valveof that common exhaust pipe will tend to flow back The placing of valvesbefore the throat prevents this back-flow taking place. In high speeds,the inertia of the exhaust steam combined with the divergent commonexhaust tends to prevent this back-flow taking place, but at low speeds,the provision of the valves, as herein illustrated and described, is

The method of operation is as follows One piston a being at-the end'ofits stroke, the valve opens to exhaust and steam V initially at theterminal cylinder pressurefiows up exhaust pipe, a and passing thethroat (Z, induces a flow of steam through the exhaust pipe 79 of theother cylinder 6. This latter exhaust pipe if, being connec ed to thecylinder, 6, the piston 6 of which is. say, at half strokeand its valvebeing still open to exhaust the back pressure on this piston, 12 isreduced. This action takes place alternately between the two cylindersaand b,from each end.

' hat I'claim and desire to secure by Letters Patent is 1. In a steamengine, branch exhaust pipes joined to a common exhaust pipe, the crosssectional area at the junction of said pipes being less than the crosssectional area of said branch pipes and non-return Valves located inSaid branch pipes. v a

2. In a steam engine, branch exhaust p pes joined to a common exhaustpipe and having their cross sectional areas contracted toward thejunction of said pipes, in combination with non-return valves in saidbranch pipes.

In testimony whereof, I have signed myname to this specification, in thepresence of two subscribing witnesses. i

' JOHN G. McKE-AN. Witnesses A. Oocnnmm MALCOLM Mo, 'ILLAN.

